The Perfect Shock?
Although the authors’ physiological analyses of the Taser seem sound [”How a Taser Works,” December 2007], I think the articles carry two flaws.
Technically, in terms of single-pulse energy integral (amperes squared per second), the 1 percent heart-fibrillation threshold is 1.5 x 10-3, the 5 percent threshold being 4 x 10-3. Therefore, the Taser single pulse, with approximately 0.6 x 10-3, seems safe by a 2.5 factor if one looks for fewer than 1 percent fatal issues. However, there are bursts of 19 pulses per second whose cumulative effects cannot be disregarded. Mark W. Kroll calculates that a 90-ampere current would be needed to electrocute someone using a Taser because its 100-microsecond pulse length is one-thirtieth that of the 3-millisecond pulses at 3 A it takes to dead-stop a heartbeat. This is not correct. Energy is related to the current squared; therefore the safety factor is not 30 but 5.5. This, too, has to be weighed by the statistical distribution of lethal current threshold.
Socially, although the benefits of disabling dangerous suspects without shooting or killing is undisputable, another issue appears: soon, criminals will get Tasers too. What a handy gizmo for a successful robbery, hold-up, or other crime, without risking capital punishment or long sentences, since no killing or injuring takes place.
The Taser article ”Crafting the Perfect Shock” by Mark W. Kroll includes a graph labeled ”Levels of Shock.” It shows Taser shock at 2 milliamperes and compares it with sine wave data at 60 hertz, which ”causes the heart to behave erratically” at about 100 mA. But the 60-Hz sine wave data are for hand-to-hand currents, which result in very low current density in the heart, whereas the Taser dart may land over the heart in the ”zone of maximum cardiac sensitivity,” which results in very high current density in the heart. A dart over the heart has been shown to cause ventricular fibrillation in pigs by Nanthakumar et al. in ”Cardiac Electrophysiological Consequences of Neuromuscular Incapacitating Device Discharges,” Journal of the American College of Cardiology , 48 (4): 798–804, 2006, and by Dennis et al. in ”Acute Effects of Taser X26 Discharges in a Swine Model,” The Journal of Trauma , 63: 581–590, 2007.
IEEE Life Fellow
What a shock that you have a person associated with the product make an assessment of the safety of the Taser [Mark W. Kroll]; he even uses the product numbers and names as if he were writing a promotional piece. You should at least have had a point (by Kroll) and a counterpoint by another, ”real” expert on the opposing side. The Tchou piece was a good addition, but that, too, was weak. There was no mention in the article of age as a factor, the assumption being that the healthy and young would be the only ones so subjected.
San Carlos, Calif.
Engineer, Get Your Gun
The article ”Build Yourself an Electric Gun” [Resources, December 2007] reminded me of how I built an electric cannon in my seventh-grade class in electricity; this takes us back to about 1944, long before silicon-controlled rectifiers became available. It was a simple device: I wound a solenoid coil around a 1/4-inch [6-millimeter] brass tube about 2 inches [5 centimeters] long and encased it in a 6-inch [15-cm] wooden barrel that I had carved on a lathe. I placed an electrical contact close to the exposed end of the brass tube, wired the device, and plugged it into a standard 120-volt receptacle. When the instrument was tilted at around 45 degrees, I could drop small steel pellets down the barrel. Then when the pellet made contact at the end of the brass tube, closing the circuit, the pellet shot out of the barrel.
IEEE Senior Member
”Build Yourself an Electric Gun” provided an interesting introduction to homemade electromagnetic (EM) weapons. It also pointed out the difficulty in obtaining the necessary components and designing an effective EM accelerator. Readers interested in experimenting with EM guns might want to check out the coil-gun pistol kit or the plans for a magnetic cannon and a single-stage electric gun available from Information Unlimited (http://www.amazing1.com).
I had one thought after reading the first paragraph from ”The R&D 100” [December 2007]: ”Toyota jumped three places to top the R&D leaderboard this year, just as it was passing General Motors to become the biggest automaker in the world. The coincidence raises a question: Are Toyota’s sales so high because of its lavish R&D spending, or is its R&D spending lavish because its sales are so high?” Neither. Dr. W. Edwards Deming and the kaizen , or continual improvement, strategy are the reasons Toyota is doing so well. GM misses the point by taking Toyota cars and tearing them apart. I am not surprised that Toyota has passed GM; it is always honing its manufacturing, looking for better ways to improve the process. Not that R&D isn’t needed, but kaizen is like R&D, as the company continually works on improving its business.
Saskatoon, Sask., Canada
Author Ron Hira responds: You make an important and excellent point. R&D captures only a small part of an organization—a few percentage points of its revenues and costs. And many of the incremental innovations that occur within an organization have little direct connection with what gets accounted for in R&D in the financial statements—for instance, many IT services firms, like Electronic Data Systems and Computer Sciences Corp., don’t report any R&D expenditures, even though they are clearly innovative.
The December 2007 issue of Spectrum contains a highly inappropriate sidebar [” The Oldest Profession” in the ” Playing Dirty” article] in which Internet prostitution and pornography are treated lightly, as a game. Internet pornography is pervasive. It is poison and addictive. Prostitution and various types of pornography are illegal in many countries. Pornography harms those who use it and their families. It can be costly to employers (for instance, use on company time) and to society as a whole.
I have seen recent painful examples. A friend in his sixties lost his job as a university professor when pornographic material was found on his computer. He spent a year in jail for it. The addiction of another friend, a retired engineer, became known. He was not arrested, perhaps for lack of provable illegal activity. In both cases family relationships were damaged irreparably. Reputations were destroyed.
Producing such material violates the IEEE Code of Ethics. Treating Internet prostitution and pornography as a game, as Spectrum did, is wrong. It is a dramatic departure from the high quality we are used to from Spectrum . The article is great free advertising for the filth merchants it named.
The IEEE should not treat this highly unethical (and in some jurisdictions, illegal) activity lightly or neutrally. Internet prostitution and pornography should not be tacitly approved or encouraged. Pornography isn’t a harmless game and it isn’t amusing. We invented the Internet. We should warn of its ”factors that might endanger the public,” as the IEEE Code of Ethics requires.
How about a well-researched Spectrum article on Internet pornography’s harmful effects? There are many solid studies on this issue.
Hyde M. Merrill
Salt Lake City
Expert Does Not Shine
Why is IEEE Spectrum quoting Nick Tredennick as an expert on global warming [”Restoring Coal’s Sheen,” Winners & Losers 2008, January 2008]? Since when does designing the 68000 microprocessor qualify him to speak as an expert on this subject? And, jarringly, this is presented in the same issue of Spectrum that claims some journalistic high ground in technology writing and criticism. A Google search finds Tredennick spouting unsupported and unscientific claims from under the shady wing of neocon pundit and Discovery Institute founder George Gilder. I have absolutely no problem with someone expressing his opinions, but when he is billed as an expert, he ought to be one.
Vancouver, B.C., Canada
The letter from Tom Schaeffer [Forum, December 2007] indicated that Google should focus on ”energy efficiency” rather than locating a data center in Oregon near ”cheap and abundant” hydropower. As a matter of fact, Google is utilizing a more efficient source of electrical energy production by going to hydro.
The overall energy conversion efficiency (potential energy of the water to electrical energy) of a hydroelectric power plant is greater than 80 percent. A coal plant’s energy conversion efficiency (chemical to electrical) is less than 50 percent because the boiler must first convert the chemical energy to steam energy. Moreover, if you take into account that the coal must be initially mined and transported to the plant site, the overall energy conversion efficiency is even lower.
An additional fact not often considered is that a hydroelectric plant uses only 2 percent of the electrical energy it produces to operate the plant’s auxiliary equipment, whereas coal plants utilize 10 to 12 percent of their produced power due to sulfur dioxide/nitrogen oxide precipitator ash handling removal requirements.
Clearly, Google is using a more energy-efficient source of power by obtaining its energy from a hydroelectric facility. If you have any doubts concerning the coal plant efficiency quoted above, please refer to the Standard Handbook for Electrical Engineers , 13th Edition, Fink and Beaty, 1993, Section 5, Generation, p. 5-5 or Marks’ Standard Handbook for Mechanical Engineers , 8th Edition, 1979, Chapter 9, Sources of Energy, p. 9–152. Pertaining to the hydroefficiency number, I can assure you that the energy conversion efficiency figure of 80 percent is quite conservative with the hydroelectric turbine generators manufactured today.
David M. Clemen
IEEE Senior Member
Western Springs, Ill.
Robert N. Charette’s piece, ”Open-Source Warfare” [November 2007] is interesting for its depiction of how terrorists can use technology wisely when confronting a massively armed invader—oh yeah, that’s us! The most stunning, perhaps self-serving, distortion Charette makes could be near the piece’s end: ”[T]he West urgently needs an insurgent-resilient process for developing and fielding effective military systems.” Of course, ”terrorist” has been oddly morphed to ”insurgent,” but the fact that we’re well on our way to expending a trillion dollars on the Iraq invasion, while depleting our armed forces and national economy, should give pause.
Didn’t we actually hear many recommendations of how to strategically deal with global terrorism before getting sucked into the Iraq mistake? Weren’t we told by experts in and out of the region that the most effective plans for success would be to raise the regional standards of health and living? Weren’t we also told that the Israeli-Palestinian issue is at the core? After all, getting people to commit suicide by blowing themselves up requires quite a level of desperation in candidate minds.
The point is, rather than expending billions or more on imagined effective hi-tech weaponry, how about doing what many folks suggested on 9/12/2001—solve the Palestinian question? After all, G.W. Bush did exactly what Bin Laden predicted—he invaded an Arab country. That didn’t work.
We can be smarter and save lots of money. The Israelis come to us for US $4 billion a year, the Palestinians are lucky to get $20 million. Just tell them both the accounts are closed until they make peaceful progress.
Menlo Park, Calif.
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